bike for 6year old with diplegia cp

hi my daughter does have a imp trike which is amazing but isnt going to last much longer for my daughter. can anyone give me advice on bikes/trikes for her or if anyone has got a bike and adapted it for your childs needs such as foot braces etc. my daughter struggles keeping her feet in one place on a bike without some support. my daughter uses splints which are amazing need something that is going to keep her feet secure. thanks to anyone with advice